Phase difference control component having columnar material

ABSTRACT

The invention has for its object the provision of a phase difference control component that, albeit comprising a phase difference control layer formed of a polymerizable liquid crystal, enables a given spacing to be maintained between opposite substrates, etc. A phase difference control component  1  comprises a multilayer structure wherein a phase difference control layer  3  formed of a liquid crystal polymer is stacked on a substrate  2 , and a plurality of prismatic, cylindrical or other columns is provided on the phase difference control layer  3 . The columns are formed of a material obtained by curing an ionizing radiation-curable resin composition. With the multilayer structure, the object of the invention can be accomplished. A black matrix, a color filter layer or the like may be interposed between substrate  2  and phase difference control layer  3 , and an electrode and an alignment film may be provided on the phase difference control layer.

BACKGROUND OF THE INVENTION

The present invention relates to a phase difference control componentthat comprises a phase difference control layer capable of improvingantireflection and viewing angle and that can keep the spacing betweenopposite substrates, etc. constant during assembly without recourse toany special means. The phase difference control component of theinvention may be applied to various displays inclusive of liquid crystaldisplays and electro-luminescence displays.

Various types of displays are put to practical use, and, for the mostpart, are used in combination with retardation films for the purpose ofimproving antireflection and/or making viewing angles wide. For atypical retardation film, a retardation film (a negative C-plate) havingits optical axis vertical to its substrate and negativedouble-refraction anisotropy and a retardation film (a positive A-plate)having its optical axis horizontal to its substrate and positivedouble-refraction anisotropy are used alone or in combination. Forinstance, see Patent Publication 1.

Currently available retardation films (herein referred to as phasedifference control components) include a stretched polycarbonate orother film, and a triacetyl cellulose film on which a liquid crystalmaterial having double-refraction anisotropy is coated. However, thereare problems in connection with reflection of light at an adhesive layerused for laminating a retardation film onto a linear polarizing plate orlaminating a multilayer structure onto a multilayer display. Moreover,the thickness of the phase difference control component itself is notthat negligible. One possible approach to solving those problemsinvolves lamination of a polymerizable polymer material onto onesubstrate that forms part of a display, thereby forming a phasedifference control component. For instance, when substrates are combinedtogether to set up a liquid crystal display, however, it is required tokeep the spacing between the opposite substrate constant. For thisreason, spacer particles such as silica particles are usually spottedover both substrates prior to lamination. For instance, see PatentPublication 2.

Patent Publication 1

JP(A)10-153802 (pp. 12-13, nd FIG. 54)

Patent Publication 2

JP(A)6-148654 (page 2)

However, one problem with the phase difference control componentfabricated using a polymerizable liquid crystal is that its rigidity isnot necessarily satisfactory. Another problem is that when the phasedifference control component is located on the inside of a substrate,spacer particles come into spot contact with the phase differencecontrol layer. Accordingly, as pressure is applied on the phasedifference control layer, it tends to suffer from deformation enoughlarge to permit spacer particles to engage therein. Thus, even whenspacer particles having a constant particle diameter are used, it isoften likely that the spacing between both substrates deviates from thediameter of the spacer particles; for instance, that spacing at thecenter of a display tends to become narrower than a given value.

SUMMARY OF THE INVENTION

It is thus the primary object of the invention to provide a phasedifference control component that, albeit comprising a phase differencecontrol layer formed of a polymerizable liquid crystal, enables a givenspacing to be maintained between opposite substrates, etc.

As a result of the inventors' studies, it has been found that if a phasedifference control component formed of a polymerizable liquid crystal isused in combination with substrate having a plurality of columns formedof a material obtained by curing an ultraviolet radiation-curable resin,it is then possible to provide a solution to the prior art problems.This finding underlies the invention.

According to the first aspect of the invention, there is provided aphase difference control component, characterized by comprising asubstrate, a phase difference control layer and a plurality of columns,wherein said phase difference control layer is stacked on said substrateand comprises a liquid crystalline polymer, and said array of columnsare provided on said phase difference control layer and formed of amaterial obtained by curing an ionizing radiation-curable resincomposition.

According to the second aspect of the invention, the first phasedifference control component of the invention is further characterizedin that each column has a sectional area of 25 μm² to 2,500 μm² and aheight of 0.5 μm to 10.0 μm.

According to the third aspect of the invention, the first or secondphase difference control component of the invention is furthercharacterized in that one column is provided per 1 to 27 pixels.

According to the fourth aspect of the invention, any one of the first tothird phase difference control components is further characterized inthat said phase difference control layer is provided for each pixel.

According to the fifth aspect of the invention, any one of the first tofourth phase difference control components is further characterized inthat a color filter layer is interposed between said substrate and saidphase difference control layer or on a side of said phase differencecontrol layer that faces away from said substrate.

According to the sixth aspect of the invention, any one of the first tofifth phase difference control components is further characterized inthat as viewed in order from said phase difference control layer on saidsubstrate, a transparent electrode layer and an alignment film arestacked thereon.

According to the seventh aspect of the invention, there is provided adisplay, characterized in that any one of the first to sixth phasedifference control components is located on a viewing side thereof.

According to the eighth aspect of the invention, there is provided anelectroluminescence display, characterized in that any one of the firstto sixth phase difference control components is located on a viewingside thereof.

According to the ninth aspect of the invention, there is provided aliquid crystal display, characterized in that any one of the first tosixth phase difference control components is located on a viewing sidethereof.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combinations of elements, and arrangements of parts, which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a), 1(b) and 1(c) are illustrative of phase difference controlcomponents having a plurality of columns.

FIG. 2 is illustrative of a phase difference control component thatfurther comprises a color filter or the like.

FIG. 3 is illustrative of the first exemplary application to a liquidcrystal display.

FIG. 4 is illustrative of the second exemplary application to a liquidcrystal display.

FIG. 5 is illustrative of the third exemplary application to a liquidcrystal display.

FIG. 6 is illustrative of the fourth exemplary application to a liquidcrystal display.

FIG. 7 is illustrative of the fifth exemplary application to a liquidcrystal display.

FIG. 8 is illustrative of the sixth exemplary application to a liquidcrystal display.

FIG. 9 is illustrative of the positions of cell gaps to be measured inone specific embodiment.

FIG. 10 is illustrative of order of stacking relative to phasedifference control layer in an embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1( a), 1(b) and 1(c) are illustrative of some basic structures ofthe phase difference control component according to the invention. Asshown in FIG. 1( a), a phase difference control component indicatedgenerally at 1 comprises a multilayer structure wherein a phasedifference control layer 3 composed of a liquid crystalline polymer isstacked on a preferably transparent substrate 2, and a plurality ofcolumnar materials or members (columns) 4 are arranged on the phasedifference control layer 3.

The term “liquid crystalline polymer” used herein is understood to referto a polymer whose liquid crystal state is immobilized at roomtemperature. For instance, the liquid crystalline polymer includes apolymer type liquid crystal wherein liquid crystal monomers havingpolymerizable groups in their molecule structures are crosslinked, andcured while their optical anisotropy before crosslinking is kept intact,and a polymer type liquid crystal having a glass transition temperature,which is heated to a temperature equal to or higher than that glasstransition temperature to yield a liquid crystal layer that is thencooled down to a temperature lower than that glass transitiontemperature to froze the liquid crystal structure.

Each column 4 may be either a prismatic column of rectangular shape insection (FIG. 1( b)) or a cylindrical column of circular shape insection (FIG. 1( c)). Besides, columns of polygonal, oval or othershapes in section may be used. Regardless of sectional shape, the columnmay have different or identical diameters at the lowermost end (on thesubstrate 2) and the uppermost end; the column may have a diameter thatchanges continuously or stepwise in its height direction. The columnhaving such basic sectional shape may also be rounded at its corners orupper end.

The column 4 should preferably have a height of about 0.5 μm to about10.0 μm, and a sectional area of about 25 μm² to about 2,500 μm². As thesectional area of the column 4 is below the lower limit of 25 μm² to thepreferable range, the column 4 is likely to become insufficient in termsof strength and adhesion strength to the underlying layer, and at morethan the upper limit of 2,500 μm², the relative magnitude of thesectional area of the column 4 to display's pixels increases, leading toadverse influences on the visibility of a matching pixel and, hence, onimage visibility. It is noted that when the lower sectional area differsfrom the upper sectional area of the column 4, the sectional area of thecolumn 4 is, by definition, given by the larger sectional area, andusually the lower sectional area in FIGS. 1( a)-1(c). The term “pixel”is here understood to refer to the smallest unit giving any one of ared, a green or a blue image subdivision. In this connection, an elementmade up of a set of one red pixel, one green pixel and one blue pixel iscalled a picture element.

Although the columns 4 may basically be arranged at random or regularly,it is preferable that the density of columns 4 is in the range of atmost about one per pixel to at least about one per 27 pixels. Whenapplied to a display, higher densities of columns render imagevisibility low, and lower densities of columns cause variations in thespacing between the phase difference control component 1 and theopposite substrate.

As shown in FIG. 2, the phase difference control component 1 of theinvention may comprise on the substrate 2 various films ordinarily usedin the art, in addition to the phase difference control layer 3 composedof a liquid crystalline polymer and the columns 4. For instance, a colorfilter layer 6 may be interposed between the substrate 2 and the phasedifference control layer 3, and a black matrix 5BM may be interposedbetween the color filter layer 6 and the substrate 2. Although the colorfilter layer 6 is shown to lie below the phase difference control layer3, it is understood that the color filter layer 6 may be placed on thephase difference control layer.

Although, in FIG. 1( a), the phase difference control layer 3 made up ofa liquid crystalline polymer is shown to be uniformly and evenly stackedon the substrate 2, it is understood that the phase difference controllayer 3 may be divided into color patterns that form the color filterlayer 6, i.e., a red pattern (shown at 6R), a green pattern (shown at6G) and a blue pattern (shown at 6B), as depicted in FIG. 2. As a matterof course, these color patterns may be dispensed with. When the phasedifference control layer 3 is provided for each color pattern, thethickness of the phase difference control layer 3 may be varieddepending on the underlying color patterns, i.e., the pixels. Thus, thephase difference control layer 3 is well fit for the application of aphase difference amount that is determined depending on the pixels, andpractically on the light wavelength of the color to be subjected tophase difference control for each pixel. The phase difference controllayer 3, whether it is a uniform, even layer or a patterned layer, mayhave a double-layer structure wherein two layers are stacked together inthe vertical direction of FIG. 1( a). It is noted that when the phasedifference control layer 3 has a double-layer structure, both layers maybe stacked on the substrate 2, one on one side, and another on anotherside. Some embodiments wherein such various layer constructions are usedtogether with the opposite substrates, etc. to set up liquid crystaldisplays are now explained with reference to the drawings.

FIG. 3, FIG. 4 and FIG. 5 are each illustrative in schematic of oneexemplary construction of a transmission type liquid crystal display towhich the phase difference control component 1 of the inventionincluding a plurality of columns is applied.

A liquid crystal display 10 shown in FIG. 3 has a multilayer structurecomprising, as viewed in order from a viewing side defined by an upperside of FIG. 3, one polarizing plate (1) 71, one substrate (1) 21 thatis transparent, a color filter layer 6, a phase difference control layer(A) 3A, a phase difference control layer (C) 3C, a plurality of columns4, a liquid crystal layer 8, an opposite substrate (2) 22 and anotherpolarizing plate (2). This liquid crystal display 10 is of thetransmission type that is viewable from its rear side defined by a lowerside of FIG. 3. In the embodiment of FIG. 3, a phase difference controlcomponent 1 of the invention including a plurality of columns is givenby a multilayer structure wherein the five layers, i.e., transparentsubstrate (1) 21, color filter layer 6, phase difference control layer(A) 3A, phase difference control layer (C) 3C and columns 4 are stackedtogether. It is here noted that FIGS. 3-8 are illustrative of therelative positions of the respective layers that are actually in contactwith one another without such spaces as shown. Throughout thedisclosure, the term “phase difference control layer (A)” refers to alayer with its optical axis lying horizontal thereto, and the term“phase difference control layer (C)” refers to a layer with its opticalaxis vertical thereto; however, the phase difference control layer usedherein may have its optical axis at an angle therewith or have aspecific hybrid orientation wherein that angle changes in the verticaldirection to that layer.

Thus, the phase difference control component of the type wherein thephase difference control layers made up of a liquid crystalline polymerare stacked together has a feature of preventing reflection of light ata bonding interface found in a structure having a separate phasedifference control component stacked on a substrate by way of anadhesive layer. Unless otherwise stated, this feature is common to allthe embodiments shown in FIGS. 3-8. Stacking of the phase differencecontrol layer uniformly all over the color filter layer 6 is not justeffective at reducing thickness variations between the respective colorpatterns that form the color filter layer 6, but is also capable ofpreventing impurities from migrating from the color filter layer 6toward the lower side of FIG. 3.

Although not shown, the phase difference control component 1 of theinvention and the liquid crystal display 10 explained with reference toFIG. 3 are subjected to such ordinary processing as mentioned justbelow. First, it is preferable that the polarizing plates 71 and 72 arebonded onto the substrates (1) 21 and (2) 22, respectively, withadhesive layers applied between them. The substrates (1) 21 and (2) 22are provided with electrodes on the opposite sides. When the electrodeis provided on the color filter layer or the phase difference controllayer, it should preferably be stacked thereon with a transparent resinprotective layer or an inorganic transparent protective layer locatedbetween them. Both substrates (1) 21 and (2) 22 are sealed up at theirperipheries while a narrow spacing is maintained by a plurality ofcolumns 4, and a liquid crystal layer 8 consisting of liquid crystals isreceived in the thus sealed spacing. On electrodes on the surfacescoming in direct contact with the liquid crystal layer 8, that is, onelectrodes on the opposite sides of the phase difference control layer(C) 3C and the substrate 2 (22) in the embodiment explained withreference to FIG. 3, alignment layers should preferably be provided. Ineach phase difference control layer, the underlying layer shouldpreferably have an alignment layer. When two phase difference controllayers are directly stacked for each phase difference control component,it is preferable that on the side of the second layer of the first phasedifference control layer, which is the underlying layer of the secondphase difference control layer, there should preferably be stacked atransparent resin protective layer and an alignment layer from the firstphase difference control layer.

A liquid crystal display 10 of FIG. 4 is similar to the liquid crystaldisplay 10 explained with reference to FIG. 3 except that the colorfilter layer 6 and both phase difference control layers (A) 3A and (C)3C change places. Accordingly, a multilayer structure wherein fivelayers, i.e., transparent substrate (1) 21, phase difference controllayer (A) 3A, phase difference control layer (C) 3C, color filter layer6 and column array 4 are stacked together in this order provides a phasedifference control component 1 of the invention including a plurality ofcolumns 4.

To the phase difference control component of the type wherein the phasedifference control layers each made up of a liquid crystalline polymeris stacked directly on the substrate (1) 21, the flatness of thesubstrate that is an underlying layer for the phase difference controllayer makes a great contribution (usually, substrates used in theseapplication fields are of excellent flatness). As a consequence, thethickness variations of the phase difference control layers are muchmore reduced with little variations in the phase difference controlfunction. Since the phase difference control layer is covered up withthe color filter layer 6, a deficiency of the surface rigidity of thephase difference control layer can be made up for by selection of thematerial of which the color filter layer 6 is formed.

A liquid crystal display 10 of FIG. 5 is similar to the liquid crystaldisplay 10 explained with reference to FIG. 4 except that the phasedifference control layer (A) 3A positioned just below the substrate (1)21 is brought onto, and stacked, on the upper surface side of thesubstrate (1) 21. Accordingly, a multilayer structure wherein fivelayers, i.e., phase difference control layer (A) 3A, transparentsubstrate (1) 21, phase difference control layer (C) 3C, color filter 6and column array 4 are stacked together in this order provides a phasedifference control component 1 of the invention including a plurality ofcolumns.

In the liquid crystal display explained with reference to FIG. 3 or FIG.4, two phase difference control layers, i.e., the phase differencecontrol layers (A) 3A and (C) 3C are directly stacked together, and soit is required to interpose a transparent resin protective layer and analignment layer between two such layers. In the liquid crystal display10 shown in FIG. 5, however, it is possible to make use of anothermultilayer structure wherein a layer made up of a liquid crystallinepolymer is limited to the phase difference control layer (C) 3C alone,and a conventional retardation film (1) 21 that is not formed of anyliquid crystalline polymer is stacked as the phase difference controllayer (A) 3A on the viewing side of the substrate (1) 21. In thisanother multilayer structure, a structure wherein four layers, i.e.,transparent substrate (1) 21, phase difference control layer (C) 3C,color filter 6 and column array 4 are stacked together in this orderprovides a phase difference control component 1 of the inventionincluding a plurality of columns, because only one phase differencecontrol layer is made up of a liquid crystalline polymer.

FIG. 6, FIG. 7 and FIG. 8 are each illustrative in schematic of oneexemplary construction of a reflection type liquid crystal display towhich the phase difference control component 1 of the inventionincluding a plurality of columns is applied.

A liquid crystal display 10 depicted in FIG. 6 has a structure wherein apolarizing plate (1) 71, one substrate (1) 21 that is transparent, acolor filter layer 6, a phase difference control layer (A) 3A, aplurality of columns 4, a liquid crystal layer 8, a reflecting plate 9and an opposite substrate (2) 22 are arranged and stacked together inorder from a viewing side that is defined by an upper side of FIG. 6.The liquid crystal display 10 is viewable through illumination from thatviewing side. The surface of the underlying layer in direct contact withthe liquid crystal layer 8 provides the reflecting plate 9 explainedwith reference to FIG. 6, and so an alignment film is preferably formedon the upper surface side of the reflecting plate 9 depicted in FIG. 6.Accordingly, a multilayer structure wherein four layers, i.e.,transparent substrate (1) 21, color filter layer 6, phase differencecontrol layer (A) 3A and column array 4 are stacked together in thisorder provides a phase difference control component of the inventionincluding a plurality of columns. It is noted that the color filterlayer 6 and the phase difference control layer (A) 3A may change places.The phase difference control component explained with reference to FIG.6 has the same advantages as those of the phase difference controlcomponent explained with reference to FIG. 3.

A liquid crystal display 10 depicted in FIG. 7 is similar to the liquidcrystal display 10 of FIG. 6 except that two phase difference controllayers, i.e., a phase difference control layer (A) 3A′ and a phasedifference control layer (A) 3A are stacked in this order on the side ofa liquid crystal layer 8 that faces away from a substrate 2.Accordingly, a multilayer structure wherein five layers, i.e.,transparent substrate (1) 21, color filter layer 6, phase differencecontrol layer (A) 3A, phase difference control layer (A) 3A′ and columnarray 4 are stacked in this order provides a phase difference controlcomponent of the invention including a plurality of columns. Oneadvantage of this arrangement is that by appropriate determination oftwo such phase difference control layers, it is possible to hold backchanges in the polarized state depending on wavelength and viewingangle.

A liquid crystal display 10 of FIG. 8 is similar to the liquid crystaldisplay 10 explained with reference to FIG. 7 except that one phasedifference control layer (A) 3A is brought onto, and stacked, on theupper surface side of the substrate (1) 21. Accordingly, a multilayerstructure wherein five layers, i.e., phase difference control layer (A)3A, transparent substrate (1) 21, color filter layer 6, phase differencecontrol layer (A) 3A′, and column array 4 are stacked together in thisorder provides a phase difference control component 1(c) of theinvention including a plurality of columns.

In the liquid crystal display explained with reference to FIG. 7, twophase difference control layers, i.e., the phase difference controllayers (A) 3A and (A) 3A′ are directly stacked together, and so it isrequired to interpose a transparent resin protective layer and analignment layer between two such layers. In the liquid crystal display10 of the structure shown in FIG. 8, however, it is possible to make useof another multilayer structure wherein a layer made up of a liquidcrystalline polymer is limited to the phase difference control layer (A)3A′ alone, and a conventional retardation film (1) 21 that is not formedof any liquid crystalline polymer is stacked as the phase differencecontrol layer (A) 3A on the viewing side of the substrate (1) 21 with anadhesive layer between them. In this another multilayer structure, astructure wherein four layers, i.e., transparent substrate (1) 21, colorfilter layer 6, phase difference control layer (A) 3A′ and column array4 are stacked together in this order provides a phase difference controlplate 1(d) of the invention including columns, because only one phasedifference control layer is made up of a liquid crystalline polymer.

In the invention, the substrate (21 and 22) may be formed of inorganicmaterials such as glass, silicon and quartz or organic materials aslisted below. That is, the organic materials include acrylics such aspolymethyl methacrylate, polyamides, polyacetals, polybutyleneterephthalates, polyethylene terephthalates, polyethylene naphthanates,triacetyl celluloses, syndiotactic polystyrenes, polyphenylene sulfides,polyether ketones, polyether ether ketones, fluororesins, polyethernitriles, polycarbonates, modified polyphenylene ethers,polycyclohexenes, polynorbornene resins, polysulfones, polyethersulfones, polysulfones, polyallylates, polyamide-imides, polyetherimides, thermoplastic polyimides or the like. Generally availableplastics may also be used. Although not critical to the invention, thethickness of the substrate 21, 22, for instance, may be on the order of5 μm to 1 mm depending on purposes.

The black matrix 5 may be formed by applying a resin composition of thecoating type containing a black coloring agent on one surface where itis temporarily cured, followed by processing with a photoresist, orcoating, exposure and development using a photosensitive resincomposition of the coating type containing a black coloring agent. Thus,the black matrix 5 may be formed of a black coloring agent-containingresin composition.

Alternatively, the black matrix 5 may be either a double-layer chromiumblack matrix having a multilayer structure of CrOx/Cr where x is anarbitrary number and / indicates a lamination or a triple-layer chromiumblack matrix having a multilayer structure of CrOx/CrNy/Cr where x and yare each an arbitrary number. Specifically, such a double- or triplechromium black matrix is provided in a thin-film form, optionally with ametal, metal oxide or metal nitride, by various processes such as ionplating or sputtering, and a thin film is then patterned byphotolithography. Those matrixes may also be provided by means ofelectroless plating or a printing process using a black ink composition.The black matrix 5 may have a thickness of the order of 0.2 μm to 0.4 μmin a thin-film form, and of the order of 0.5 μm to 2 μm when prepared byprinting.

While the color patterns of the color filter layer 6 are provided foreach opening in the black matrix 5, it is understood that they mayoptionally be provided in a strip form extending from the front of FIG.2 in the depth direction. The color filter layer 6 is formed of a resincomposition in which a coloring agent is dissolved or dispersed, orpreferably a finely divided pigment is dispersed. For instance, inkcompositions colored in given colors are printed for each color pattern.However, it is more preferable that the color filter layer 6 is formedby photolithography using a photosensitive resin composition of thecoating type containing a coloring agent of given color. The colorfilter layer 6 has a thickness on the order of 1 μm to 5 μm.

The color patterns that form the color filter layer 6 are usuallyprovided at the same thickness; however, the thickness of the phasedifference control layer provided corresponding to the color patternsvaries with colors. Accordingly, when the phase difference control layeris provided on a color filter layer that has had color patterns ofvarying thicknesses, it is preferable that both the layers are providedin such a way that the total of the thickness of the color patterns andthe thickness of the phase difference control layer is kept constant,thereby permitting the phase difference control layer to have an optimumvalue for each color pattern. When the color filter layer is providedwith a thickness larger than usual, it is preferable to decrease theamount of the coloring agent added, and when provided with a thicknesssmaller than usual, it is preferable to increase the amount of thecoloring agent added. Coating thickness may be controlled by changingthe coating or printing conditions, or changing the viscosity of thecoating or ink composition used.

Prior to providing the phase difference control layer 3 on the colorfilter layer 6, an alignment film for the phase difference control layer3 is provided, if necessary. This alignment film is provided to line upthe liquid crystalline polymer for forming the upper phase differencelayer 3 in a given direction. The alignment film may be formed bycoating and drying a resin composition with a polyamide or polyimideresin dissolved therein to form a resin coating film, and grubbing thatresin coating film in a given direction using a cloth-wound roller orthe like. It is noted that when two phase difference control layers arestacked together, it is preferable to interleave an alignment filmbetween the first and the second layer. When the phase differencecontrol layer 3 is stacked directly on the substrate 2, too, it ispreferable to provide an alignment film.

The phase difference control layer 3 is formed of a material obtained bycuring a polymerizable liquid crystal composition that contains apolymerizable liquid crystal compound. The phase difference controllayer (A) referred to in the foregoing, that is, the phase differencecontrol layer with its optical axis horizontal thereto may be formed bythe polymerization of a polymerizable liquid crystalline monomer.Specifically, a photopolymerizable liquid crystal composition comprisinga photopolymerization initiator incorporated in such a monomer is coatedon an application surface, and then exposed to ultraviolet radiation orthe like. The phase difference control layer (C), that is, the phasedifference control layer having its optical axis vertical thereto andnegative refractive index anisotropy may be formed in the same manner asmentioned above with the exception that a photopolymerizable liquidcrystal composition having a polymerizable chiral agent incorporatedtherein is used.

For the polymerizable liquid crystal monomer, those known fromJP(A)10-508882 may be used, and for the polymerizable chiral agent,those known from JP(A)7-258638 may be used. Specifically, thepolymerizable liquid crystal monomer may be exemplified by the followingstructural formulae (1) and (11), and the polymerizable chiral agent maybe exemplified by the following structural formulae (12) to (14).

In structural formulae (11) to (14), small letters a, b, c, d and eindicative of the number of methylene groups (the chain lengths ofalkylene groups) are each an integer. Small letters a and b are eachindependently 2 to 12, preferably 4 to 10, and more preferably 6 to 9; cand d are each independently 2 to 12, preferably 4 to 10, and morepreferably 6 to 9; and e is 2 to 5. A capital Y in structure formulae(12) and (13) is any one of formulae (i) to (xxiv) in groups (15) and(16), and preferably formula (I), (ii), (iii), (v) or (vii).

To provide the phase difference control layer 3 on the color filterlayer 6, such a photopolymerizable liquid crystal composition,optionally dissolved in or diluted by a solvent, is coated on the colorfilter layer 6 by means of spin coating, die coating, slit coating orother suitable processes, and then polymerized by ultravioletirradiation.

Only one requirement for the phase difference control layer 3 is topermit it to sit on the color patterns that form the color filter 6; theaforesaid exposure process is carried out by such a pattern exposurethat only the necessary places are left behind, so that the phasedifference control layer 3 can be stacked on only an effective displayarea that receives the color filter layer 6, the black matrix 5 and soon, with nothing on the peripheral edge of the substrate 2. If the phasedifference control layer 3 is stacked in place in this way while theperipheral edge of the substrate 2 remains exposed, it is then possibleto ensure that a sealing material is applied on the exposed peripheraledge of the substrate 2, when the phase difference control component ofthe invention including a plurality of columns is applied to a liquidcrystal display.

Each column 4 may be formed of various materials; in view of strength,however, that should preferably be formed of a material obtained bycuring a curable resin. In consideration of the ability to locate thecolumn 4 of given size in given place, the column 4 should preferably beformed of a cured material of a photosensitive resin composition, andbroadly a cured material of an ionizing radiation-curable resincomposition. Specifically, the ionizing radiation-curable resin isprocessed, if required, as a mixture with a solvent, a diluent, amonomer or the like and, optionally, with additives into a coating orink composition for preparing columns. This composition is thenprocessed by means of a photo-process (photolithography) involvingcoating, drying, given pattern exposure and development. In this way,the desired column 4 may be obtained. Alternatively, the column 4 may beobtained by a printing process or the like suitable for thick coating,if required, followed by multiple printing. While the invention will beexplained exclusively with reference to the photosensitive resincomposition, it is understood that materials cured by irradiation withelectron radiation other than ultraviolet radiation could also be used.

For the formation of the column 4, the photosensitive resin compositionis coated on an application surface to a given thickness, if required,followed by preliminary curing. Subsequently, the coating is exposed tolight in a given pattern using a mask or the like, and then developed.Thus, the column 4 formed of the organic material is well compatiblewith other layers, and preferably for this photosensitive resincomposition, compositions containing a photosensitive resin having areactive vinyl group such as a resin based on acrylate, methacrylate,polycinnamic acid or cyclized rubber are used. The photosensitive resincomposition generates relatively less heat to an application member. Itis noted that the column 4 could also be formed of an inorganic materialsuch as silicon oxide or silicon. Although a large amount of heat isrequired for the formation of such an inorganic column, it has somemerits of being well compatible with an inorganic substrate such as aglass substrate and free from solvent or other bleeding.

When the column 4 is formed of an inorganic material, it is preferablethat a film is formed by vapor phase growth such as vapor deposition orsputtering, and then patterned by photolithography.

When the phase difference control component of the invention comprisesthe color filter layer 6 as explained with reference to FIG. 2, aplurality of columns 4 may be formed using an exclusive material.Alternatively, photosensitive resin compositions for forming the red,green and blue divisions that provide the color filter layer 6 may beused to provide a plurality of columns 4 by photolithography.Specifically, at least two or three of the photosensitive resincompositions for forming the red, green and blue divisions are put oneupon another in the thickness direction to obtain a plurality of columns4 having the desired sufficient thickness. This enables material andprocess steps to be much more saved as compared with the use of theexclusive material. It is noted that a plurality of higher columns 4could be provided on the black matrix 5.

While the phase difference control component of the invention having aplurality of columns has been described specifically with reference tothe liquid crystal display, especially the color liquid crystal display,it is understood that the phase difference control component of theinvention may also be applied to a self-emission type display such as anorganic EL display, a field emission display or a plasma display.

As shown in FIG. 10, the phase difference control component 1 of theinvention may comprise on the substrate 2 a phase difference controllayer 3, a transparent electrode layer 23, columns 4 and alignment filmlayer 24.

EXAMPLES

Photosensitive resin compositions (hereinafter called photoresists) forforming the black matrix and the color patterns for the color filterlayer provided on the substrate were prepared. Each photoresist wasprepared by mixing a resist composition comprising polymers, monomers,additives, initiators and solvents with a dispersion obtained bydispersing together pigments, dispersants and solvents plus beads for 3hours using a paint shaker as a dispersing machine and removing thebeads from the resulting dispersion. Each photoresist was composed ofthe following ingredients in the following parts given on a weightbasis.

Black Matrix-Formation Photoresist

Black Pigment (TM Black #9550 made by 14.0 parts Dainichi Seika Co.,Ltd.) Dispersant (Disperbick 111 made by Big 1.2 parts Chemy Co., Ltd.Polymer ((Meth)Acrylic Resin Product No. 2.8 parts VR60 made by ShowaKobunshi Co., Ltd.) Monomer (Polyfunctional Acrylate Product No. 3.5parts SR399 made by Sartomer Co., Ltd.) Additive (Dispersion Improver;Chemitory L-20 0.7 part Soken Kagaku Co., Ltd.) Initiator(2-benzyl-2-dimethylamino-1-(4- 1.6 parts morpholinophenyl)-butaonone)Initiator (4,4′-diethylaminobenzophenone) 0.3 part Initiator(2,4-diethylthioxanthone) 0.1 part Solvent (Ethylene Glycol MonobutylEther) 75.8 partsRed Pattern-Formation Photoresist

Red Pigment (C.I. PR254) 3.5 parts (Chromophthal DPP Red BP made byChiba Specialty Chemicals Co., Ltd) Yellow Pigment (C.I. PY139) 0.6 part(Paliotol Yellow D1819 made by BASF) Dispersant (Solperse 24000 made byZeneca 3.0 parts Co., Ltd.) Polymer 1* 5.0 parts Monomer (PolyfunctionalAcrylate Product No. 4.0 parts SR399 made by Sartomer Co., Ltd.)Initiator (Irgacure 907 made by Chiba 1.4 parts Specialty Chemicals Co.,Ltd.) Initiator (2,2-bis(o-chlorophenyl)-4,5,4′,5′- 0.6 parttetraphenyl-1,2′-bisimidazole) Solvent (Propylene Glycol MonomethylEther 80.0 parts Acetate) Polymer 1* is an adduct of 16.9 mol % of2-methacryloyloxyethyl isocyanate to 100 mol % of a copolymer of benzylmethacrylate:styrene:acrylic acid:2-hydroxymethyl methacrylate =15.6:37.0:30.5:16.9 (molar ratio), with a weight-average molecularweight of 42,500.Green Pattern-Formation Photoresist

This photoresist was prepared with the same ingredients as in the redpattern-formation photoresist with the exception that instead of the redand yellow pigments, the following pigments were used in the amountsspecified below.

Green Pigment (C.I. PG7) 3.7 parts (Seika Fast Green 5316P made byDainichi Seika Co., Ltd.) Yellow Pigment (C.I. PY139) 2.3 parts(Paliotol Yellow D1819 made by BASF Co., Ltd.)Blue Pattern-Formation Photoresist

This photoresist was prepared with the same ingredients as in the redpattern-formation photoresist with the exception that instead of the redpigment, yellow pigment and dispersant, the following ingredients wereused in the amounts specified below.

Blue Pigment (C.I. PB15:6) 4.6 parts (Heliogenble L6700F made by BASFCo., Ltd.) Purple Pigment (C.I. PV23) 1.4 parts (Fosterperm RL-NF madeby Clariant Co., Ltd.) Pigment Derivative 0.6 part (Solperse 12000 madeby Zeneca Co., Ltd.) Dispersant 2.4 parts (Solperse 24000 made by ZenecaCo., Ltd.)

A molten process borosilicate thin-sheet glass having a thickness of 0.7mm (Product No. 7059 made by Coning Co., Ltd., U.S.A.) was provided as asubstrate. After the substrate was washed, a black matrix-formationphotoresist was coated thereon by spin coating, after which the coatingwas prebaked at a temperature of 90° C. for a heating time of 3 minutes.Then, the prebaked coating was exposed to a given pattern of ultravioletradiation at an irradiation dose of 100 mJ/cm². After that exposure,spray development was carried out for 60 seconds using a 0.05% aqueoussolution of KOH. Finally, post-baking was performed at a temperature of200° C. for a heating time of 30 minutes to form a 1.2-μm thick blackmatrix having openings corresponding to pixels.

Then, a red pattern-formation photoresist was spin coated on the blackmatrix provided on the substrate, after which the coating was prebakedat a temperature of 80° C. for a heating time of 5 minutes. Then, theprebaked coating was subjected to alignment exposure in a given patternat an irradiation dose of 300 mJ/cm². After that exposure, spraydevelopment was carried out for 60 seconds using a 0.1% aqueous solutionof KOH. Finally, post-baking was performed at a temperature of 200° C.for a heating time of 60 minutes to form a 2.6-μm red pattern atpositions corresponding to the given openings in the black matrix.

Subsequently, a green pattern-formation photoresist and a bluepattern-formation photoresist were used as was the case with the redpattern-formation photoresist to form a 2.6-μm thick green pattern and a2.6-μm thick blue pattern. In this way, the red, green and blue patternswere formed in alignment with the positions of different openings in theblack matrix to make a color filter layer with red, green and bluethree-color patterns formed in alignment.

An alignment film-formation ink composition of polyimide resin (ProductNo. AL1254 made by JSR Co., Ltd.) was pattern printed on the necessarysite on the color filter layer on the black matrix on the substrate bymeans of flexographic printing. After that printing, the pattern wasdried for solvent removal, and then fired at a temperature of 200° C.for a heating time of 1 hour, after which the fired pattern was rubbedat the surface to form an alignment film of 700 Å in thickness.

Photosensitive resin compositions (A) and (C) were prepared for theformation of phase difference control layers (A) and (C). Thephotosensitive resin composition (A) was prepared by mixing 75 parts ofa liquid crystal material having a mesogen at its center, polymerizableacrylate groups at both its terminals and a spacer between the centermesogen and the terminal acrylate groups with 1 part of aphotopolymerization initiator (1-hydroxycyclohexyl phenyl ketone;Irgacure 184 made by Chiba Specialty Chemicals Co., Ltd.) and 25 partsof a solvent toluene, and the photosensitive resin composition (C) wasprepared by mixing a composition similar to the photosensitive resincomposition (A) with 5 parts of a chiral material having polymerizableacrylate groups at both its terminals.

The photosensitive resin composition (A) for the formation of the phasedifference control layer was spin coated on the alignment film, afterwhich the assembly including the substrate was placed on a hot platewhere it was heated at a temperature of 100° C. for a heating time of 5minutes for solvent removal to allow the coating to grow a liquidcrystal structure therein. After this, pattern exposure was carried outwith a 365-nm wavelength ultraviolet radiation at an irradiation dose of10 J/cm², and development was done using a methanol developing solutionto form a 1.0-μm thick phase difference control layer (A) on the greenpattern on the color filter layer. The same steps were repeated with theexception that the mask openings were displaced during pattern exposureto form a 1.3-μm thick phase difference control layer (A) on the redpattern and a 0.75-μm thick phase difference control layer (A) on theblue pattern.

Subsequently, the photosensitive resin composition (C) was used as wasused as in the case of the formation of the phase difference controllayer (A) to form a 2.5-μm thick phase difference control layer (C) onthe phase difference control layer (A) on the green pattern of the colorfilter layer. The same steps were repeated with the exception that themask openings were displaced during pattern exposure to form a 2.3-μmthick phase difference control layer (C) on the phase difference controllayer (A) on the red pattern and a 2.7-μm thick phase difference controllayer (C) on the phase difference control layer (A) on the blue pattern.

An ultraviolet curing type of overcoat-formation coating compositionwith an acrylic resin used as a binder resin was coated on a divisionwith the phase difference control layers (A) and (C) arranged in order,and then dried on a hot plate for solvent removal. Subsequently, patternexposure was done using a photomask, and development was then done forremoval of unexposed regions, after which post-baking was effected toform an overcoat layer of 1.2 μm in thickness. Finally, a 2,000-Å thickITO (indium tin oxide) thin film was formed as a common electrode on thethus formed overcoat layer by means of sputtering.

An ultraviolet curable, transparent negative type resist was coated onthe thus formed ITO thin film, and then subjected to pattern exposureand development, thereby forming a plurality of columns having a heightof 4.5 μm and an ITO thin film-side bottom area of 100 μm² at aproportion of 1 per 240 μm×240 μm. After the formation of the columns, apattern form of polyimide resin-based alignment agent (JALS2021 made byJSR Co., Ltd.) was applied by flexographic printing on a division withthe phase difference control layers (A) and (C) as well as the columnsformed thereon, and then fired at a temperature of 200° C. for 1 hour toform a 700-Å thick vertical alignment film. In this way, a phasedifference control component having a plurality of columns was obtained.

An opposite substrate was obtained by successively providing the sameITO thin film and vertical alignment film on the same substrate by thesame process as described above. This opposite substrate was put on theabove phase difference control component having a plurality of columnswith the vertical alignment films opposite to each other, and theperipheral edges of the assembly were then bonded together and sealed upto form a square cell having an internal size of 10 cm×10 cm. A liquidcrystal having negative dielectric anisotropy (Product No. MLC6608 madeby Merck & Co., Inc.) was injected and sealed up in that cell by meansof vacuum injection. Finally, after-annealing was carried out at atemperature of 110° C. for 1 hours for cancellation in the flowingdirection, thereby obtaining a liquid crystal cell.

COMPARATIVE EXAMPLE

A comparative liquid crystal cell was obtained as in the examples withthe exception that a phase difference control component prepared with nocolumns provided thereon was placed on an opposite substrate wherein4.5-μm diameter spacer beads (Micropearl made by Sekisui Chemical Co.,Ltd.) were spotted over an alignment film.

An LCD cell gap-measurement system (Product No. MCPD2000 made by OtsukaElectronics Co., Ltd.) was used to measure cell gaps (liquid crystallayer thickness) regarding the inventive and comparative liquid crystalcells obtained as described above. The values in μm of cell gapsmeasured per 1.4 cm in directions from the point of intersection ofdiagonals of the square contour of the cell along the diagonals towardthe upper side of FIG. 9 are given in Table 1. It is noted that theencircled numbers 1 to 9 in Table 1 correspond to the encircled numbersin FIG. 9.

TABLE 1 {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} {circle around (5)} Inventive 4.208 4.202 4.2164.214 4.217 Comparative 4.441 4.214 4.256 4.450 4.430 {circle around(6)} {circle around (7)} {circle around (8)} {circle around (9)}Inventive 4.211 4.220 4.207 4.204 Comparative 4.411 4.220 4.314 4.330

As can be seen from Table 1, the largest and smallest cell gap values inthe inventive example are 4.220 μm and 4.202 μm, respectively; thedifference between the largest and the smallest is as small as 0.018 μm,whereas the largest and smallest cell gap values in the comparativeexample are 4.450 μm and 4.214 μm, respectively; the difference betweenthe largest and the smallest is as large as 0.236 μm.

The first aspect of the invention can provide a phase difference controlcomponent that makes it easy to set the spacing between oppositesubstrates at a predetermined value and reduce variations in thatspacing without causing spacer particles to engaging in a phasedifference control layer as found in the prior art, because a pluralityof columns stacked on that phase difference control layer and formed ofa material obtained by curing an ionizing radiation-curable resincomposition is utilized for the purpose of limiting the spacing betweenopposite substrates.

The second aspect of the invention can provide a phase differencecontrol component that has not just the advantage of the first aspect ofthe invention but also can maintain strength and image visibility whenapplied to a display, because each column is predetermined in terms ofsectional area and height.

The third aspect of the invention can provide a phase difference controlcomponent that has not just the advantage of the first or second aspectof the invention, but can also reduce variations in image visibility andthe spacing between opposite substrates, because the density of columnsis defined in terms of the number of pixels.

The fourth aspect of the invention can provide a phase differencecontrol component that has not just the advantage of the first, secondor third aspect of the invention, but is also well suited for giving adifferent amount of phase difference for each pixel, because the phasedifference control layer is provided for each pixel.

The fifth aspect of the invention can provide a phase difference controlcomponent that has not just the advantage of any one of the first tofourth aspects of the invention, but can also make chromatic correction,because the color filter layer is provided.

The sixth aspect of the invention can provide a phase difference controlcomponent that enables a liquid crystal layer to be immediatelyinterposed between opposite substrates, because a transparent electrodelayer and an alignment layer are stacked on the phase difference controllayer in this order.

The seventh aspect of the invention can provide a display that makes themost of the advantage of any one of the phase difference controlcomponents according to the 1^(st) to 6^(th) aspects of the invention.

The eighth aspect of the invention can provide an electroluminescencedisplay that makes the most of the advantage of any one of the phasedifference control components according to the 1^(st) to 6^(th) aspectsof the invention.

The ninth aspect of the invention can provide a liquid crystal displaythat makes the most of the advantage of any one of the phase differencecontrol components according to the 1^(st) to 6^(th) aspects of theinvention.

1. A phase difference control member adapted to be employed in a displaycell, comprising a substrate, a phase difference control layer andcolumns, wherein said phase difference control layer has a first facethat is stacked on said substrate and comprises a liquid crystallinepolymer, and said columns are provided at a second face of said phasedifference control layer and formed of a material obtained by curing anionizing radiation-curable resin composition, wherein said second faceof said phase difference control member is opposite said first face ofsaid phase difference control layer that is stacked on said substrateand said second face side is adapted to be oriented toward a displaycomponent when assembled in the display cell, further comprising a colorfilter layer is interposed between said substrate and said phasedifference control layer or on a side of said phase difference controllayer that faces away from said substrate.
 2. The phase differencecontrol member according to claim 1, further comprising each column hasa sectional area of 25 μm² to 2,500 μm² and a height of 0.5 μm to 10.0μm.
 3. The phase difference control member according to claim 1 or 2,further comprising when said phase difference control component is usedto construct a display comprising a plurality of pixels, columns formedon the phase difference layer are such that one column is provided per 1to 27 of said pixels.
 4. The phase difference control member accordingto claim 1 or 2, further comprising that as viewed in order from saidphase difference control layer on said substrate, a transparentelectrode layer and an alignment film are stacked on the phasedifference control layer in the noted order and, wherein said columnsand said alignment layer are both stacked on said transparent electrodelayer.
 5. A display, comprising that the phase difference control memberaccording to claim 1 or 2 is located on a viewing side thereof.
 6. Aliquid crystal display, comprising that the phase difference controlmember according to claim 1 or 2 is located on a viewing side thereof.